Telephone-receiver.



A. S. MOFFAT. TELEPHONE RECEIVER. APPLICATION FILED Alma, 1914.

L., PatentedSept. 7, 1915.

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ALBERT S. MOFAT, 0F BELMONT, MASS MASSACHUSETTS.

TELEPHONE-RECEIVER.

Specification of Letters Patent.

A]Pate1rrted Sept. '7, 1915.

Application led August 8, 1914. Serial No. 855,890.

To all whom 'it may concern Be it known that l, ALBERT S. MOFFAT,residing at Belmont, in the county of Middlesex and Commonwealth ofMassachusetts, a citizen of the United States, have invented certain newand useful Improvements in Telephone-Receivers, of which the -followingis a full, clear, and exact description.

This invention has to do with telephone receivers used in connection'with loudspeaking telephones, and has for its purpose the effecting ofimprovements in details of construction as hereinafter set forth, andillustrated in the drawings forming part of this specification, in whichFigure 1 is a central longitudinal section of a receiver embodying myimprovements. Fig. 2 is a detail view on a larger scale of the laterallyadjustable pole piece.' Fig. 3 is a face view of the longitudinallyadjustable pole piece. Fig. 4 is an end view of the same andv of itswindings. Fig. 5 is a perspective view of the armature.

' The reference numeral 1 designates the receiver case, preferablycylindrical in formation, and having a cap 2 suitably aiiixed thereto,as by the screwhreaded flange 3. Fitted tightly within the upper part ofsaid case is a cup 4 between which and said cap is secured the erablycomposed of mica. To said cap'is secured a horn 7 or other means for thedirection of the sound-waves.

` Diametrically across the case is secured a bar 10, preferably' held byscrews 11 and by a leg 12 attached to the bottom of the case.\ Said barhas a transversely disposed slot 13 in which slidably fits theadjustable pole piece 14 whose stem 15 is threaded and extends outthrough the pole piece 14 is surrounded by the oblong core 20 upon whichthe coil 21 is wound, and is preferably slidable therein, said core ancoil being fastened in any suitable manner to the bar 10. For thusmoving said pole piece, in' order to present it as near to the armatureas possible, without danger of actual contact, and thereby to producethe maximum effect upon the armature and hencevupon the diaphragm, asleeve 16 is provided for the stem 1.5 and formed with a shoulder thecase l. This sleeve being threaded both internally and externally to. tsaid stem diaphragm 5 by means of rubber rings 6, said diaphragm beingprefend of the armature case-bottom. rlfhe 1 d' 25 at its point ofattachment to the 17 bearing against the interior of' and to enter a nut19, the latter being outside the case, the proper rotation of both nutand sleeve will present the pole piece at the desired point ofadjustment. Slidable on said bar 10 is the pole piece 22 held in placethereon by 'a small set screw 23, and resting against the outer end ofthe pole piece is an end of the armature 24. From the opposite end ofthe latter extends a slender elbow 25 attached to the center of thediaphragm by small nuts 26.

lVhen pulsatory current is delivered to the coil 21, as by talking intoa transmitter at the other end of the line, the pole piece 14 variablyattracts the armature in the usual way and thereby vibrates thediaphragm. Since the point of attachment to the diaphragm is nearlytwice as far from the pole as is the pole 14, the amplitude of vibrationimparted to the diaphragm will be correspondingly magnified, and thesound emitted thereby will beafar louder than would be the case were saipoint of attachment directly over the pole `piece 14. By adjusting thepole 22, which'v serves as the fulcrum for the armature, nearer to thecoil, the loudness of sound will be still further increased and viceversa.

Rising from the pole piece 22 is a slight lug 27 fitting in a slot orgroove 29 in the armature 24. The engagement of said lug and grooveserves to keep the armature later ally in place on the said pole piece,while permitting the adjustment of the latter relative to the pole-piece14.

y It is evident that the magnetic attraction between the pole piece 22and the contacting will retain the latter in place thereon when there isany current in circuit, but when the receiver is being shipped or put instorage, such attraction would be absent and there would be danger ofthe armatures swinging laterally on the ellow 1aphragm as a center, andso becoming badly displaced.

What l claim is:

1. A telephone' receiver comprising an electromagnet having vits polesin the same transverse plane, an armature, andV a diaphragm centrallyconnected with one end of said armature, the end of the armature fartherremoved from said diaphragm being slidably supported by one of saidpoles and its other end being in the field 0f the other 110 pole, thearmature-supporting pole being adjustable toward and from the otherpole, whereby the leverage of the armature is changed Without affectingits position.

2. A telephone receiver comprising an electromagnet having its poles inthe same transverse plane, an armature, and a diaphragm centrallyconnected with one end of said-armature, the other end of the armaturebeing supported by one of said poles, the latter being adjustable towardand from the other pole, and it and the armature having means forkeeping the armature from lateral displacement. j

3. A telephone receiver comprising an electromagnet having its poles inthe same transverse plane, an armature, and a diaphragm centrallyconnected With one end of said armature,

aving a longitudinally disposed groove, one of said poles beingadjustable toward and from, the other pole and having a lug engagingsaid groove.v

4. A- telephone receiver comprising a diaphragm, a case supporting thesame, an armature parallel With the diaphragm and connected at one endWith the latter, a pole piece supported rigidly by the case with itsfield' close to the end ofthe armature connected With the diaphragm,windings about said pole piece, a second pole piece parallel With and inmagnetic connection with the the other end of the latter f first polepiece and 'adjustable toward and from the same, the first namedpole-piece being tubular, a core longitudinally movable in the tubularpole-piece, and means operative eXteriorly ofthe case for longitudinallyadjusting the core, the end of the arma` ture not connected With thediaphragm being lslidably supported by the second-named pole-piece.

5. A telephone receiver comprising a horse shoe magnet, a fulcrumedarmature, and a diaphragm connected with one end of said armature, saidmagnet having a longitudinally adjustable pole presented to the end ofsaid armature connected with said diaphragm, the said adjustment beingaccomplished by means of ay threaded stem projecting from the pole, ashouldered sleeve internally and externally threaded and turning on saidstem, and a nut on said sleeve, the receiver having a case penetrated bysaid stem and sleeve, the shoulder of said sleeve abutting against theinner surface of the case, and said nut abutting against the outersurface thereof.

In testimony that I claim the foregoing invention, I have hereunto setmy hand this 7th day of August, 1914.

' ALBERT S. MOFFAT.

Witnesses:

A. B. UPHAM, WM. H. KUNz.

